Help!! Need bike info

A lot depends on your budget and what your plans are. Having just researched this very topic over the last 3 months I'll sum a few basic things:

Most people start on a road bike for 2 main reasons. Price (Tri bikes are more) and compatibility with other cyclists (Tri bikes + road bikes don't coexist for group riding).

I also believe there is an experience factor when deciding what type of bike to buy because like anything new, there is a learning curve with proper and safe use  of the gear.

I think of it something like driving a car for the first time at 16: most parents take their kids out on the street infront on their residence rather then taking them onto the datona 500 race course and drive a stock car....

Bike anatomy:

Shifters: These are the brake/shifters up on the handlebars

deraileurs: responsible for shifting the front and back gears

cassette: the collection of cogs (gears) on the rear wheel.  You can swap out different cassettes depending on the kind of terrain and the kind of rider you are. 

Cranks: These are the arms that attach to the pedals of the bike, as well as the two (sometimes three) front chain rings.

Fork: this is the part of the bike that holds the front wheel to the frame

Bikes have different quality levels of parts (frame/shifters/deraileurs/cassette/crank) that make the bike better and therefore cost more.  Here are some ball park figures for name brand bikes (like Trek, Felt, Giant, Specialized, Cannondale etc).

Shimano 2300 (shifters/deraileurs) ~ 700 $

Shimano sora (shifters/deraileurs) ~ 900 $

Shimano Tiagra (shifters/deraileurs) ~1200 $

Shimano 105 (shifters/deraileurs) ~ 1500 $

And there are more options but those are out of my price range so I don't know anything about them.

The NUMBER ONE thing to remember is to get the bike fitted!!!.

That sums up a few basics. I hope it helps.